Dissecting the activation of insulin degrading enzyme by inositol pyrophosphates and their bisphosphonate analogs

• Published in: Chemical science (Cambridge) 2021-08, Vol.12 (32), p.1696-172
• Main Authors: Hostachy, Sarah, Utesch, Tillmann, Franke, Katy, Dornan, Gillian Leigh, Furkert, David, Türkaydin, Berke, Haucke, Volker, Sun, Han, Fiedler, Dorothea
• Format: Article
• Language: English
• Subjects: Analogs; Binding sites; Bisphosphonates; Chemistry; Enzymes; Insulin; Metabolites; Molecular docking; Molecular dynamics; Phosphate esters; Reagents; Substrates
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d1sc02975d

Inositol poly- and pyrophosphates (InsPs and PP-InsPs) are densely phosphorylated eukaryotic messengers, which are involved in numerous cellular processes. To elucidate their signaling functions at the molecular level, non-hydrolyzable bisphosphonate analogs of inositol pyrophosphates, PCP-InsPs, have been instrumental. Here, an efficient synthetic strategy to obtain these analogs in unprecedented quantities is described - relying on the use of combined phosphate ester-phosphoramidite reagents. The PCP-analogs, alongside their natural counterparts, were applied to investigate their regulatory effect on insulin-degrading enzyme (IDE), using a range of biochemical, biophysical and computational methods. A unique interplay between IDE, its substrates and the PP-InsPs was uncovered, in which the PP-InsPs differentially modulated the activity of the enzyme towards short peptide substrates. Aided by molecular docking and molecular dynamics simulations, a flexible binding mode for the InsPs/PP-InsPs was identified at the anion binding site of IDE. Targeting IDE for therapeutic purposes should thus take regulation by endogenous PP-InsP metabolites into account. An efficient synthesis of non-hydrolyzable inositol pyrophosphate analogs was developed to subsequently investigate the regulation of insulin-degrading enzyme by these hyperphosphorylated signaling molecules.